More specifically, the invention relates to a pneumatic brake booster comprising a rigid casing locally shaped into a hollow shaft pierced with an opening, a moving partition, a hub secured to the moving partition, an annular seal and position-setting means, the moving partition sealingly delimiting front and rear chambers of variable and complementing volumes inside the rigid casing, the hub being cylindrical and slideably mounted in the opening of the hollow shaft between a rest position and at least one active position, the seal being arranged between the hub and the hollow shaft, and the position-setting means fixing the rest position of the hub with respect to the casing.
Devices of this type are well known in the prior art as illustrated, for example, by patent documents U.S. Pat. No. 3,470,697, FR-2 532 084 and FR-2 658 466.
In spite of the relatively traditional nature of the technique concerned, boosters continue to be the subject of research aimed at further reducing the costs of manufacture without incurring any reduction in their reliability.